The father of a key prosecution witness in the sexual abuse trial of former Penn State University assistant football coach Jerry Sandusky on Wednesday told jurors his son was "distraught" when he called to report he had seen Sandusky molesting a boy.

John McQueary, the father of former graduate assistant coach Mike McQueary, said his son called him directly after witnessing the incident in a locker room shower, which Mike McQueary also described in testimony on Tuesday.

"His description to me was a slapping, rhythmic kind of thrusting, slapping sound," John McQueary said he was told by his son. That is similar to the description of the incident Mike McQueary already provided to the court.

John McQueary told his son to leave the Penn State athletic facilities immediately and the two then met at their home to discuss the incident further, he said. They agreed that Mike McQueary should report the incident.

"We determined that it was imperative to report this to the authorities at Penn State," John McQueary said. They agreed to report it to Mike McQueary's direct supervisor, head football coach Joe Paterno.

The elder McQueary's statements kicked off the third day testimony in the high-profile case, which has shaken Pennsylvania State University and its long-successful football program and prompted the firing of Paterno, the winningest coach in major U.S. college football history. He died of lung cancer in January.

The case has also brought national attention to the issue of child sexual abuse.

On Tuesday, the Centre County courtroom fell silent when a sobbing teenage witness told jurors he was 10 or 11 years old when Sandusky befriended him through a charity he ran, the Second Mile, and later sexually abused him.

Sandusky eventually performed oral sex on him, the 18-year-old witness said. "I didn't want it to happen," he said, his head bowed.

Sandusky, 68, faces 52 counts of abusing 10 boys over a 15-year period. If convicted on all counts, he faces a sentence of more than 500 years in prison.

Mike McQueary testified on Tuesday that he had seen Sandusky and a boy between 10 and 12 in a shower at a Penn State locker room in February 2001. The boy has not been identified.

McQueary said he saw Sandusky behind the boy and both were naked.

There were "skin-on-skin slapping sounds, yes. Sex," the former coach said.

Sandusky's defense attorneys, Joe Amendola and Karl Rominger, questioned McQueary's testimony, pointing out discrepancies in accounts to police and a grand jury about the date of the alleged incident and at what point the boy had seen him.

They also said the 18-year-old witness and McQueary were looking to get money out of the case. The teenage witness has hired an attorney, and McQueary, who lost his job as an assistant coach, has said he is planning a whistleblower suit against the university.

Two accusers have testified, and an additional six are scheduled to take the stand. Judge John Cleland has said the trial should run until the end of the month.